Former Premier Kristina Keneally says she did not authorise the sale just before her government lost power.

Paul Miller: AAP

Former New South Wales premier Kristina Keneally has told a Sydney court she did not authorise the purchase of the former union-owned retreat, Currawong.

The purchase of the land in Sydney's north was made in the final weeks of her government.

Ms Keneally is giving evidence in the trial of former lands department boss, Warwick Watkins.

Mr Watkins was charged after an Independent Commission Against Corruption (ICAC) inquiry into the debacle.

He is accused of using a backdated letter to give the impression he was authorised to make the purchase.

Ms Keneally has told the court she gave Mr Watkins the authority to enter negotiations with the developer that owned the property, but not to proceed with the final purchase and close the $12 million deal.

The former premier says she is still angry about the purchase of the Currawong holiday retreat.

"I feel incredibly angry and frustrated and disappointed about the events that occurred in March 2011 in relation to this site," she said.

Ms Keneally says she has always been consistent in her recollection of what happened.

"Well as I have stated previously and I have testified today that the sale appeared to have occurred without authorisation from the executive level of government," she said.

"Certainly there was no approval given by me or by any committee of cabinet. Further it occurred at a time when the government was clearly in caretaker mode."

Ms Keneally says she will provide whatever evidence is necessary to assist the court with the administration of justice.